Equivalent-particle approximations in electron and photon processes of higher-order QED

Abstract

The method of equivalent-photon and -lepton approximations is applied to speedy estimates of higher-order QED cross sections in high-energy electron-positron annihilation and inelastic photon- and electron-nucleon scattering. The equivalent-particle spectra are derived with infinite-momentum-frame techniques. The limitations of the approximation scheme are discussed thoroughly.